In Japan, there have long been used Lactobacillus preparations as drugs for controlling intestinal functions, which have considerably high safety. Moreover, there have also been put on the market a variety of so-called health foods for controlling intestinal functions, which contain lactic acid bacteria. In addition, yogurt and fermented milk comprising lactic acid bacteria, conventionally favorably ingested as health foods have recently been admitted as specific health foods for controlling the gastrointestinal conditions and have thus attracted special interest. On the other hand, lactic acid bacteria-containing drugs and foods have likewise been attracted special interest as representatives of “probiotics products”, which show not only the effect of controlling intestinal functions, but also other various functions and are thus effective for maintaining the user's health, even in Europe and America and various kinds of products have commercially been available. For this reason, lactic acid bacteria have widely been investigated for the study and development of various probiotics products (Reuter G.: Intraintestinal Flora and Probiotics (edited by MITSUOKA Tomotari), pp. 17–39, published by Gakkai Shuppan Center, 1998).
The term “probiotics” is in general defined to be “living microorganisms capable of improving the balance of the enterobacterial flora in a host to thus bring beneficial effects on the host” (Fuller R.: Gut, 1991, 32:439–42). In addition, it has been reported that the probiotics typically represented by lactic acid bacteria possess a wide variety of functions as will be detailed below (Sanders M E & Huis in't Veld J: Antonie van Leeuwenhoek, 1999, 76: 293–315): 1) Assistance of lactose-digestion; 2) resistance to enterobacteria; 3) inhibition of the occurrence of colon cancer; 4) inhibition of small intestinal bacteria-excess proliferation; 5) immuno-modulating effects; 6) anti-allergic effects; 7) effects of reducing blood lipid concentration; 8) hypotensive effects; 9) inhibition of urinary tract-infection; 10) inhibition of Helicobacter pylori infection; and 11) inhibition of hepatic encephalopathy. Moreover, it has also been proved that the tooth-brushing with lactic acid bacteria is quite effective even for the prevention or treatment of periodontitis (IMAI, Tatsuya: Tooth-Brushing with Lactic Acid Bacteria for Curing Periodontitis Within 3 Days, published by MAKINO Publishing Company, 2000).
As has been discussed above, it has been elucidated that the probiotics may improve the balance of not only the enterobacterial flora, but also bacterial florae in oral cavity, stomach and other digestive tracts as well as urinogenital bacterial flora such as the intra-vaginal flora to thus bring beneficial effects on the host. It would be recognized that lactic acid bacteria are adhered to mucous membranes of digestive tracts and urinogenital organs, proliferate thereon, and produce useful metabolites such as lactic acid to directly or indirectly make the barrier function of mucous membranes of digestive tracts and urinogenital organs normal or healthy and to thus show the foregoing effects or functions.
Lactic acid bacteria to be used in probiotics products are selected on the basis of the criteria or requirements such as the stability, the resistance to the acid in the stomach, the resistance to bile, the stability during manufacture of a product or the stability of the bacteria in the product, the adhesion to mucous membranes, the bacterial inhibitory effects and the ability of stimulating immuno responses (Sanders M E & Huis in't Veld J: Antonie van Leeuwenhoek, 1999, 76: 293–315). As strains, which satisfy the foregoing requirements, principally used herein are lactic acid bacteria belonging to the genuses Lactobacillus, Streptococcus and Bifidobacterium, which are indigenous lactic acid bacteria found in the human digestive tract. In particular, the lactic acid bacteria belonging to the genus Lactobacillus have most frequently been used. Among them, preferentially selected and practically used are strains such as Lactobacillus rhamnosus GG strain (Japanese Un-Examined Patent Publication (hereunder referred to as “J. P. KOKAI”) Sho 61-280433), Lactobacillus casei Shirota strain (commercially available under the trade name of “Yakult”), Lactobacillus johnsonii La1 strain (J. P. KOKAI Hei 6-315373), Lactobacillus plantarum 299 strain (DMS 6595) (TOKUHYO Hei 6-501624), L. plantarum 299v strain (DMS 9843) (TOKUHYO Hei 11-502703), Lactobacillus salivarius UCC 1 strain (NCIMB 40830) and L. salivarius UCC 118 strain (NCIMB 40829) (WO 98/35014).
When these lactic acid bacteria-containing probiotics products are administered to animal and human bodies, however, a problem arises such that the lactic acid bacteria are discharged soon from, for instance, digestive tract and therefore, the products fail to maintain and show the desired functions of probiotics.